The present invention relates to devices having deployable ultrasound transducers for performing endometrial ablation.
Menorrhagia is a common problem in women that is characterized by extended or irregular menstrual cycles or excessive amounts of bleeding during menstrual cycles. The endometrium is the uterine lining which is responsible for the bleeding that occurs during menstrual cycles, as well as dysfunctional uterine bleeding. Heating to at least superficially destroy the endometrium, also known as endometrial ablation, has been shown to reduce the aforesaid abnormal bleeding. In some cases ablating the endometrium results in cessation of the menstrual bleeding altogether, which may be preferable to the irregular cycles and excessive bleeding that otherwise occur.
There are many technologies on the market and in clinical trials which utilize a range of energy sources, but the goal for each is the same, i.e., endometrial tissue destruction by thermal cryo-coagulation. For example, Neuwirth, et al, xe2x80x9cThe Endometrial Ablator: A New Instrumentxe2x80x9d, Obst. and Gyn., 1994, Vol. 83, No. 5, Part 1, 792-796, performed endometrial ablation using a dextrose-filled balloon device mounted at the end of a carrier catheter and including a heating element inside the balloon. This device also includes a system that monitors the pressure and temperature inside the balloon. Neuwirth, et al. determined that if the surface of the balloon-tissue interface is maintained at about 90xc2x0 C. for 7-12 minutes, the depth of damage to the endometrium was about 4-10 millimeters. This depth of damage is believed to be clinically acceptable to the extent that such a procedure could be considered as an alternative to surgical procedures, such as hysterectomy.
High frequency, or radiofrequency (RF), energy has been used to ablate the endometrium as well as cryo-techniques. For example, Prior, et al., xe2x80x9cTreatment of Mennorrhagia By Radiofrequency Heatingxe2x80x9d, Int. J. Hyperthermia, 1991 Vol. 7, No. 2, 213-220, achieved a significant reduction in dysfunctional uterine bleeding using a device that includes a probe having a high frequency RF energy source that is inserted directly into the patient""s uterus through the vagina and cervix. The energy source is an RF system having an electrode on the probe and a belt placed around the patient that serves as the return electrode. This RF system is operated at 27.12 MHz at a power of 550 Watts for about 20 minutes and achieves a deeper penetration than the Neuwirth, et al. device, which is an advantage over the Neuwirth, et al. device.
A system marketed under the tradename THERMACHOICE(copyright), by Ethicon, Inc. of Somerville, N.J., is currently used to perform endometrial ablation and includes a latex balloon filled with a heated dextrose and water solution. The balloon is attached to the distal end of a catheter carrier and the device often delivers satisfactory results. Some patients, however, present a need for deeper and broader endometrial penetration during ablation.
U.S. Pat. No. 5,620,479 discloses a device for thermal treatment having an array of tubular piezoelectric transducers disposed on a semi-flexible tubular carrier for delivering ultrasound energy directly to tissue to be ablated. The transducers are covered with a sealant coating and there is an outer covering over the sealant coating. This device also includes thermocouple sensors embedded in the sealant coating over each transducer for continuous monitoring of the tissue-applicator interface temperatures for feedback control of the power delivered to the transducers.
U.S. Pat. No. 5,733,315 also discloses a device for ablating tissue using ultrasound energy, but is adapted specifically for insertion into the rectum for treating the prostate. This device includes one or more ultrasound transducers disposed at least partly about a support tube, each ultrasound transducer having inactivated portions for reducing ultrasound energy directed to the rectal wall. The transducers of this device are also enclosed in a sealant.
U.S. Pat. No. 5,437,629 discloses an apparatus and method for recirculating heated fluid in the uterus to perform endometrial ablation, without using a balloon. U.S. Pat. No. 5,769,880 discloses an apparatus and method for performing tissue ablation, including endometrial ablation, using bipolar RF energy. This device includes an electrode-carrying member mounted to the distal end of a shaft and an array of electrodes mounted to the surface of the electrode carrying member. A vacuum is utilized to draw out vapors, which are created when the tissue is ablated.
The foregoing devices and techniques are all either too complex or provide less than optimal results. In addition, they all deliver energy in a general manner, without the ability to control or direct the application of energy in situ to the tissue to be treated. It is further noted that there are no devices specifically adapted for endometrial ablation that use therapeutic ultrasound.
The device of the present invention addresses the shortcomings of the existing apparatus and process for endometrial ablation by providing a device that delivers ultrasound energy to the endometrial tissue in a controlled and efficient manner by having deployable piezoelectric transducers mounted on movable carriers that are deployed after insertion into the uterus.
A device for thermal ablation therapy having emitting means for emitting ultrasound energy capable of heating tissue and moving means for moving the emitting means between an undeployed position, in which the emitting means is in a first orientation which facilitates insertion of the device, and a deployed position, in which the emitting means is in a different second orientation that is selected to efficiently deliver ultrasound energy to the tissue to be ablated. The emitting means is movable from the undeployed position to any one of an infinite number of orientations for efficiently delivering ultrasound energy to the tissue. The moving means is one or more movable carriers and the emitting means is one or more piezoelectric transducers that are securely mounted on the carriers for conjoint movement therewith.
The moving means includes a rod which has a distal end and a proximal end, and a hollow sleeve, which has a through passage. The rod is slideably received in the through passage and the distal end of the rod is connected to a carrier, whereby sliding movement of the rod moves the piezoelectric transducer or transducers mounted thereon between the undeployed and deployed positions. The piezoelectric transducer and the sleeve are linearly arranged relative to each other when the piezoelectric transducer is in its undeployed position. When the piezoelectric transducer is in its deployed position, the piezoelectric transducer and the sleeve are arranged relative to each other in a non-linear manner. In addition, moving means may also include a handle having a movable part that is connected to the proximal end of the rod for moving the piezoelectric transducer between its undeployed and deployed positions in response to movement of the movable part of the handle.
In one embodiment, a set of first transducers is mounted linearly on a first carrier and a set of second transducers is mounted linearly on a second carrier. When the first and second transducers are in their undeployed positions, the first transducers are arranged linearly relative to the sleeve and the second transducers are also arranged linearly relative to the sleeve. When the first and second transducers are in their deployed positions, the first transducers are arranged at an angle relative to the sleeve and the second transducers are arranged at an angle relative to the sleeve and relative to said second transducers
In another embodiment, a plurality of transducers are mounted linearly on a carrier. When the transducers are in their undeployed positions, they are arranged linearly relative to the sleeve and when the transducers are in their deployed positions, they are arranged perpendicularly relative to the sleeve.
In still another embodiment, a first carrier has a first transducer mounted thereon and a second carrier includes a second transducer mounted thereon and the first and second carriers are pivotable relative to one another such that the first and second transducers are movable between their undeployed and deployed positions. When the first and second transducers are in their undeployed positions the first and second transducers are both arranged linearly relative to the sleeve. When the first and second transducers are in their deployed positions, the first and second transducers are oriented substantially perpendicularly relative to the sleeve and the first and second transducers are arranged linearly relative to one another.
A method for thermal ablation therapy using ultrasound energy involves positioning an ultrasound device in an undeployed position in which said ultrasound device in is a first orientation which facilitates positioning of the device proximate to tissue to be heated; moving the ultrasound device from its undeployed position to a deployed position which is selected to efficiently deliver ultrasound energy to tissue to be heated; and activating the ultrasound device to emit ultrasound energy for a predetermined period of time.